The present invention relates in general to locking devices for telephone instruments, and more particularly to a locking device for a telephone instrument having a depressible key or button for dialing.
Heretofore, telephone locking devices have been employed to lock telephone instruments having dials rotatable by an operator's finger. A locking device for such an instrument would have a removable key that caused the actuation of a clamp for entering the finger hole to prevent the rotation of the dial. In order to use the telephone instrument, the locking device was removed from the penetrated finger hole and the clamp was removed from clamping engagement with the rotatable dial.
Another locking device heretofore employed to lock telephone instruments, which had either a rotatable dial or a depressible dialing element, required the handset of the telephone instrument to be removed from the cradle. After the handset was removed from the cradle of the telephone instrument, the locking device depressed a cradle plunger and retained the cradle plunger in a depressed state. The telephone instrument could not be operated with the cradle plunger depressed.
The locking devices heretofore employed for locking telephone instruments with depressible dialing elements were found to be unduly expensive and unduly inconvenient.
In the patent to Roof, U.S. Pat. No. 3,780,234, issued on Dec. 18, 1973, for Lock For Press Button Telephones, there is disclosed a key controlled device having conductors connected to the Touch Toner key circuit. The locking device included key actuated switches to make or break the circuit connection to the Touch Tone key circuit.
The patent to Richards, Sr., U.S. Pat. No. 3,712,964, issued on Jan. 23, 1973, for Lock for Telephone Instrument describes a locking device that is disposable within the cradle of the telephone instrument. When the body of the locking device is disposed within the cradle of the telephone instrument, the body depresses a cradle plunger of the telephone instrument. After the cradle plunger is depressed, a locking key for the locking device is actuated to pivot a locking member of the locking device into locking engagement with the base of the telephone instrument. To release the cradle plunger, the locking key is actuated to disengage the pivotal member of the locking device from the base of the telephone instrument and the locking device is removed from the cradle of the telephone instrument.
The patent to Mendenbach, U.S. Pat. No. 2,864,906, issued on Dec. 16, 1958, for Locking Device For French Phone, discloses a locking device that clamps the handset of the telephone instrument in the cradle of the telephone instrument by engagement with the base of the telephone instrument. While the handset is locked in the cradle, the cradle plunger is depressed.
The patent to Bart, U.S. Pat. No. 3,495,050, issued on Feb. 10, 1970, for Telephone Lock describes a telephone dial shield that is locked to the base of the telephone instrument.
In the patent to Buckingham, U.S. Pat. No. 3,624,317, issued on Nov. 30, 1971, for Telephone Lock, there is disclosed a locking device with a base plate that seats in the cradle of the telephone instrument between the cradle plungers. A locking plate is detachably secured by a cylindrical lock and cam to the base plate of the telephone instrument. When the locking plate is so secured, the locking plate engages the cradle plungers of the telephone instrument to depress the cradle plungers. When the locking plate is removed from the base plate, the cradle plungers are released.
A similar arrangement is disclosed in the patent to Wagoner, U.S. Pat. No. 3,939,678, issued on Feb. 24, 1976, for Telephone Locking Apparatus, and in the patent to Edelcreek, U.S. Pat. No. 3,723,671, issued on Mar. 27, 1973, for Telephone Lock. See also the patent to Benson, U.S. Pat. No. 2,641,659, issued on June 9, 1953, for Telephone Lock and the patent to Foote, U.S. Pat. No. 3,598,931, issued on Aug. 10, 1971, for Telephone Set Locks. Other patents of interest are the patent to Rudolph, U.S. Pat. No. 3,823,277, issued on July 9, 1974, for Telephone Locking Device and the patent to Nimer, U.S. Pat. No. 3,069,513, issued on Dec. 18, 1962, for Telephone Clamps.